High performance thermoplastic polymers, such as polyetherimides and polyethersulfones have been used to fabricate parts for numerous applications. Each application requires particular tensile and flexural properties, impact strength, heat distortion temperature, and resistance to warp. For example, U.S. Pat. No. 4,455,410 provides a polyetherimide-polyphenylenesulfide blend having good flexural strength characteristics. U.S. Pat. No. 3,983,093 provides polyetherimide compositions having improved solvent resistance and suitable for use in preparing films, molding compounds, coatings, and the like.
These thermoplastic polymers are characterized by a high glass transition temperature, typically above 150xc2x0 C., which makes them suitable for use in applications that require exposure to high temperatures. A drawback of these materials is that they exhibit poor melt flow properties, which makes processing difficult. Injection molding of thermoplastic polymers, for instance, is more easily performed with a thermoplastic resin that has a higher melt volume rate. A good melt flow behavior is necessary to achieve fast molding cycles and to permit molding of complex parts. At the same time, mechanical properties such as impact/ductility must be maintained in order to pass product specifications.
What is needed in the art is thermoplastic polymers that have improved melt flow behavior without the consequent loss of other desirable characteristics in the finished product.
The present invention overcomes the limitations of the prior art by incorporating additives into thermoplastic polymer resins. In one embodiment, this invention comprises a thermoplastic resin composition comprising a mixture, based on the total weight of the thermoplastic resin composition, of about 88 wt % to about 99 wt % pbw of a thermoplastic polymer resin; and, about 1 wt % to about 12 wt % of an additive selected from the group consisting of phosphonium sulfonate, anhydride, and combinations thereof.
It has been found that (aromatic) phosphonium sulfonates as well as (aromatic) anhydride compounds provide highly improved melt flow properties to high performance thermoplastic polymers such as polycarbonates, polyimides (e.g. polyetherimides, polyamideimides, etc.), amorphous polyamides, polysulfones (e.g. polyethersulfones, polyarylsulfones, polyphenylsulfones (PPSU), etc.), poly ketones (e.g. poly(ether ketone), poly(ether ether ketone), etc.), polyphenylene sulfoxide, and poly(phenylene sulfoxide) (PPSO2), mixtures thereof, and the like and other high performance thermoplastic resins, without causing detrimental effects on other physical properties, such as mechanical and impact properties.
The high performance thermoplastic polymer of the present invention comprises a thermoplastic polymer preferably having a glass transition temperature exceeding about 150xc2x0 C., preferably exceeding about 170xc2x0 C., such as polycarbonates, polyimides (e.g. polyetherimides, polyamideimides, etc.), amorphous polyamides, polysulfones (e.g. polyethersulfones, polyarylsulfones, polyphenylsulfones (PPSU), etc.), poly ketones (e.g. poly(ether ketone), poly(ether ether ketone), etc.), polyphenylene sulfoxide, poly(phenylene sulfoxide) (PPSO2), mixtures thereof, and the like; and an anhydride or a phosphonium sulfonate. Other additives are optionally added to the high performance thermoplastic polymer to improve other desirable characteristics.
Polyamide
The polyamide resins useful in the practice of the present invention are a generic family of resins known as amorphous polyamides or amorphous nylons, characterized by the presence of an amide group (xe2x80x94C(O)NHxe2x80x94). Nylon-6 and nylon-6,6 containing aromatic substituents, e.g., phthalamide residues, are the generally preferred amorphous polyamides and are available from a variety of commercial sources. Useful amorphous polyamides, include, for example, nylon-4,6T, nylon-12T, nylon-6,10T, nylon 6,9T, nylon 6/6T and nylon 6,6/6T although other amorphous nylons may be employed. Mixtures of various amorphous polyamides, as well as various amorphous polyamide copolymers, are also useful. The most preferred amorphous polyamide for the blends of the present invention is an amorphous polyamide-6,6 containing isophthalamide residues.
The polyamides can be obtained by a number of well known processes such as those described in U.S. Pat. Nos. 2,071,250, 2,071,251, 2,130,523, 2,130,948, 2,241,322, 2,312,966, 2,512,606, 5,177,149 (which are hereby incorporated by reference), and others. Nylon-6,6T is a condensation product of adipic acid, phthalic acid(s) and 1,6-diaminohexane. Likewise, nylon 4,6T is a condensation product between adipic acid, phthalic acid(s) and 1,4-diaminobutane. Besides adipic acid, other useful diacids for the preparation of nylons include azelaic acid, sebacic acid, dodecane diacid, as well as terephthalic and isophthalic acids, and the like. Other useful diamines include m-xylyene diamine, di-(4-aminophenyl)methane, di-(4-aminocyclohexyl)methane; 2,2-di-(4-aminophenyl)propane, 2,2-di-(4-aminocyclohexyl)propane, among others. Copolymers of caprolactam with diacids and diamines are also useful.
Amorphous polyamides having viscosity of up to and even exceeding about 400 ml/g can be used, with a viscosity of about 90 to about 350 ml/g preferred, and about 110 to about 240 ml/g especially preferred, as measured in a 0.5 wt % solution in 96 wt % sulphuric acid in accordance with ISO 307. Additionally, it is often preferred for the amorphous polyamide to have a very low amine endgroup level to avoid reactions with the anhydrides. Alternatively, the phosphonium sulfonate may preferably be used when the amorphous polyamide contains more than about 5% amine endgroups.
Thermoplastic Polyimides and Polyetherimides
Useful thermoplastic polyimides have the general formula (I) 
wherein V is a substituted or unsubstituted, divalent, trivalent, or tetravalent linker without limitation, as long as the linker does not impede synthesis or use of the polyimide. Suitable linkers include but are not limited to: (a) substituted or unsubstituted, saturated, unsaturated or aromatic monocyclic and polycyclic groups having about 5 to about 50 carbon atoms, (b) substituted or unsubstituted, linear or branched, saturated or unsaturated alkyl groups having from 1 to about 30 carbon atoms; and combinations thereof. Suitable substitutions and/or linkers include, but are not limited to, ethers, epoxides, amides, esters, and combinations thereof.
R in formula (I) includes but is not limited to substituted or unsubstituted divalent organic radicals such as: (a) aromatic hydrocarbon radicals having about 6 to about 20 carbon atoms and halogenated derivatives thereof; (b) straight or branched chain alkylene radicals having about 2 to about 20 carbon atoms; (c) cycloalkylene radicals having from about 3 to about 20 carbon atoms, or (d) divalent radicals of the general formula (II) 
wherein Q includes but is not limited to divalent radicals of the formula (III) 
wherein y is an integer of from 1 to about 5; or combinations thereof.
Preferred classes of polyimides include polyamidimides and polyetherimides, particularly those polyetherimides known in the art which are melt processible, such as those whose preparation and properties are described in U.S. Pat. Nos. 3,803,085 and 3,905,942, each of which is incorporated herein by reference.
Preferred polyetherimide resins comprise more than 1, typically about 10 to about 1000 or more, and more preferably about 10 to about 500 structural units, of the formula (IV) 
wherein T is xe2x80x94Oxe2x80x94 or a group of the formula xe2x80x94Oxe2x80x94Zxe2x80x94Oxe2x80x94 wherein the divalent bonds of the xe2x80x94Oxe2x80x94 or the xe2x80x94Oxe2x80x94Zxe2x80x94Oxe2x80x94 group are in the 3,3xe2x80x2, 3,4xe2x80x2, 4,3xe2x80x2, or the 4,4xe2x80x2 positions, and wherein Z includes, but is not limited to, divalent radicals of formula (V). 
wherein Q includes but is not limited to divalent radicals of the formula (III) 
wherein y is an integer of from 1 to about 5; or combinations thereof.
In one embodiment, the polyetherimide may be a copolymer that, in addition to the etherimide units described above, further contains polyimide structural units of the formula (VI) 
wherein R is as previously defined for formula (I) and M includes, but is not limited to, radicals of formula (VII). 
The polyetherimide can be prepared by any of the methods well known to those skilled in the art, including the reaction of an aromatic bis(ether anhydride) of the formula (VIII) 
with an organic diamine of the formula (IX)
H2Nxe2x80x94Rxe2x80x94NH2xe2x80x83xe2x80x83(IX)
wherein T and R are defined as described above in formulas (I) and (IV).
Examples of specific aromatic bis(ether anhydride)s and organic diamines are disclosed, for example, in U.S. Pat. Nos. 3,972,902 and 4,455,410, which are incorporated herein by reference. Illustrative examples of aromatic bis(ether anhydride)s of formula (VIII) include: 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride; 4,4xe2x80x2-bis(3,4-dicarboxyphenoxy)diphenyl ether dianhydride; 4,4xe2x80x2-bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride; 4,4xe2x80x2-bis(3,4-dicarboxyphenoxy)benzophenone dianhydride; 4,4xe2x80x2-bis(3,4-dicarboxyphenoxy)diphenyl sulfone dianhydride; 2,2-bis[4-(2,3-dicarboxyphenoxy)phenyl]propane dianhydride; 4,4xe2x80x2-bis(2,3-dicarboxyphenoxy)diphenyl ether dianhydride; 4,4xe2x80x2-bis(2,3-dicarboxyphenoxy)diphenyl sulfide dianhydride; 4,4xe2x80x2-bis(2,3-dicarboxyphenoxy)benzophenone dianhydride; 4,4xe2x80x2-bis(2,3-dicarboxyphenoxy)diphenyl sulfone dianhydride; 4-(2,3-dicarboxyphenoxy)-4xe2x80x2-3,4-dicarboxyphenoxy)diphenyl-2,2-propane dianhydride; 4-(2,3-dicarboxyphenoxy)-4xe2x80x2-(3,4-dicarboxyphenoxy)diphenyl ether dianhydride; 4-(2,3-dicarboxyphenoxy)-4xe2x80x2-(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride; 4-(2,3-dicarboxyphenoxy)-4xe2x80x2-(3,4-dicarboxyphenoxy)benzophenone dianhydride and 4-(2,3-dicarboxyphenoxy)-4xe2x80x2-(3,4-dicarboxyphenoxy)diphenyl sulfone dianhydride, as well as various mixtures thereof.
The bis(ether anhydride)s can be prepared by the hydrolysis, followed by dehydration, of the reaction product of a nitro substituted phenyl dinitrile with a metal salt of dihydric phenol compound in the presence of a dipolar, aprotic solvent. A preferred class of aromatic bis(ether anhydride)s included by formula (VIII) above includes, but is not limited to, compounds wherein T is of the formula (X) 
and the ether linkages, for example, are preferably in the 3,3xe2x80x2, 3,4xe2x80x2, 4,3xe2x80x2, or 4,4xe2x80x2 positions, and mixtures thereof, and where Q is as defined above.
Suitable organic diamines of formula (IX) include, for example: m-phenylenediamine; p-phenylenediamine; 4,4xe2x80x2-diaminodiphenylpropane, 4,4xe2x80x2-diaminodiphenylmethane (commonly named 4,4xe2x80x2-methylenedianiline); 4,4xe2x80x2-diaminodiphenyl sulfide; 4,4xe2x80x2-diaminodiphenyl sulfone; 4,4xe2x80x2-diaminodiphenyl ether (commonly named 4,4xe2x80x2-oxydianiline); 1,5-diaminonaphthalene; 3,3-dimethylbenzidine; 3,3-dimethoxybenzidine; 2,4-bis(beta-amino-t-butyl)toluene; bis(p-beta-amino-t-butylphenyl)ether; bis(p-beta-methyl-o-aminophenyl)benzene; 1,3-diamino-4-isopropylbenzene; 1,2-bis(3-aminopropoxy)ethane; benzidine; m-xylylenediamine; 2,4-diaminotoluene; 2,6-diaminotoluene; isomeric methyl4,6-diethyl-1,3-phenylenediamines; bis(2-chloro-4-amino-3,5-diethylphenyl)methane; bis(4-aminocyclohexyl)methane; 3-methylheptamethylenediamine; 4,4-dimethylheptamethylenediamine; 2,11-dodecanediamine; 2,2-dimethylpropylenediamine; 1,18-octamethylenediamine; 3-methoxyhexamethylenediamine; 2,5-dimethylhexamethylenediamine; 2,5-dimethylheptamethylenediamine; 3-methylheptamethylenediamine; 5-methylnonamethylenediamine; 1-4-cyclohexanediamine; 1,18-octadecanediamine; bis(3-aminopropyl)sulfide; N-methyl-bis(3-aminopropyl)amine; hexamethylenediamine; heptamethylenediamine; nonamethylenediamine; decamethylenediamine and mixtures of such diamines.
In a particularly preferred embodiment, the polyetherimide resin comprises structural units according to formula (IV) wherein each R is independently paraphenylene or metaphenylene or a mixture thereof and T is a divalent radical of the formula (XI) 
Included among the many methods of making the polyimides, particularly polyetherimides, are those disclosed in U. S. Pat. Nos. 3,847,867, 3,814,869, 3,850,885, 3,852,242, 3,855,178, 3,983,093, and 4,443,591. These patents are incorporated herein by reference for the purpose of teaching, by way of illustration, general and specific methods for preparing polyimides.
In general, the reactions can be carried out employing well-known solvents, e.g., o-dichlorobenzene, m-cresol/toluene and the like to effect a reaction between the anhydride of formula (VIII) and the diamine of formula (IX), at temperatures of about 100xc2x0 C. to about 250xc2x0 C. Alternatively, the polyetherimide can be prepared by melt polymerization of aromatic bis(ether anhydride)s (VIII) and diamines (IX) by heating a mixture of the starting materials to elevated temperatures with concurrent stirring. Generally melt polymerizations employ temperatures of about 200xc2x0 C. to about 400xc2x0 C. Chain stoppers and branching agents may also be employed in the reaction. When polyetherimide/polyimide copolymers are employed, a dianhydride, such as pyromellitic anhydride, is used in combination with the bis(ether anhydride). The polyetherimide resins can optionally be prepared from reaction of an aromatic bis(ether anhydride) with an organic diamine in which the diamine is present in the reaction mixture at no more than about 0.2 molar excess, and preferably less than about 0.2 molar excess. Under such conditions the polyetherimide resin has less than 15 microequivalents per gram (xcexceq/g) acid titratable groups, and preferably less than about 10 xcexceq/g acid titratable groups, as shown by titration with chloroform solution with a solution of 33 wt % hydrobromic acid in glacial acetic acid. Acid-titratable groups are essentially due to amine end-groups in the polyetherimide resin.
Generally, useful polyetherimides have a melt index of about 0.1 to about 10 grams per minute (xe2x80x9cg/minxe2x80x9d), as measured by American Society for Testing Materials (xe2x80x9cASTMxe2x80x9d) D1238 at 295xc2x0 C., using a 6.6 kilogram (xe2x80x9ckgxe2x80x9d) weight. In a preferred embodiment, the polyetherimide resin has a weight average molecular weight (Mw) of about 10,000 to about 150,000 grams per mole (xe2x80x9cg/molexe2x80x9d), as measured by gel permeation chromatography, using a polystyrene standard. Such polyetherimide resins typically have an intrinsic viscosity [xcex7] greater than about 0.2 deciliters per gram, preferably about 0.35 to about 0.7 deciliters per gram measured in m-cresol at 25xc2x0 C. Some such polyetherimides include, but are not limited to Ultem 1000 (number average molecular weight (Mn) 21,000; weight average molecular weight (Mw) 54,000; dispersity 2.5), Ultem 1010 (Mn 19,000; Mw 47,000; dispersity 2.5), Ultem 1040 (Mn 12,000; Mw 34,000-35,000; dispersity 2.9), or mixtures thereof.
Poly(ether)sulfone
Polyethersulfone is a thermoplastic polymer having the general formula shown by Formula XII: 
where Z is a divalent radical according to Formula V. Some specific examples include:
wherein Z is of the formula: 
xe2x80x83which corresponds to Polyphenylene sulfone such as Radel R by AMOCO,
wherein Z is of the formula: 
xe2x80x83and Y is SO2, which corresponds to polyethersulfone, such as Ultrason E commercially available from BASF Aktiengesellschaft, Ludwigshafen, Germany, or Y is C(CH3)2 which corresponds to Polysulfone such as Ultrason S commercially available from BASF, or Udel commercially available from BP AMOCO, Chicago, Ill.; and Z is a mixture of phenylene and diphenyl sulfone which corresponds to polyarylsulfone such as Radel A commercially available from AMOCO; as well as mixtures thereof, and others. In addition, 
xe2x80x83corresponds to polyphenylenes ulfoxide, PPSO2.
The polyethersulfone resins useful with the present invention include all those known in the art which are melt processible, such as those whose preparation and properties are described in U.S. Pat. Nos. 4,959,454, 4,310,654, 5,830,974, 5,229,482, each of which is incorporated herein by reference, and others.
(Aromatic) Phosphonium Sulfonates
The phosphonium sulfonate compounds that improve the melt flow properties of the high performance thermoplastic resins have the basic structure as shown in formula (XVI): 
wherein A is an alkyl group with 1 to about 36 carbon atoms, alkenyl group with about 4 to about 24 carbon atoms, phenyl group, phenyl group substituted by alkyl group with 1 to about 18 carbon atoms, naphthyl group or naphthyl group substituted by alkyl group with 1 to about 18 carbon atoms, R1, R2 and R3 are preferably identical, each being an aliphatic hydrocarbon group with 1 to about 8 carbon atoms or aromatic hydrocarbon group, and R4 is a hydrocarbon group with 1 to about 18 carbon atoms.
A preferred phosphonium sulfonate is tetrabutylphosphonium dodecylbenzenesulfonate (EPA-202, available from Takemoto Oil and Fat Co.) (i.e., Formula XVI with A=p-dodecyl benzene and R1xe2x95x90R2xe2x95x90R3xe2x95x90R4xe2x95x90Butyl (xe2x80x94C4H9)). Others include tetrabutyl phosphonium benzene sulfonate (A=Benzene and R1xe2x95x90R2xe2x95x90R3xe2x95x90R4xe2x95x90Butyl), tetrabutyl phosphonium methane sulfonate (A=Methyl and R1xe2x95x90R2xe2x95x90R3xe2x95x90R4xe2x95x90Butyl), tetrabutyl phosphonium trifluoromethane sulfonate (A=TrifluoroMethane and R1xe2x95x90R2xe2x95x90R3xe2x95x90R4xe2x95x90Butyl), tetrabutyl phosphonium perfluorobutyl sulfonate (A=Perfluorobutane (CF3CF2CF2CF2xe2x80x94) and R1xe2x95x90R2xe2x95x90R3xe2x95x90R4xe2x95x90Butyl) or tetrabutyl phosphonium diphenylsulfon sulfonate (A=Diphenylsulfone and R1xe2x95x90R2xe2x95x90R3xe2x95x90R4xe2x95x90Butyl),
(Aromatic) Anhydrides
Aromatic anhydrides also improve the melt flow properties of the thermoplastic resins of this invention, and, in a preferred embodiment, have the basic structures shown in at least one of the formulas XVII: 
wherein the divalent T moiety bridges the 3,3xe2x80x2, 3,4xe2x80x2, 4,3xe2x80x2, or 4,4xe2x80x2 positions of the aryl rings of the respective aryl anhydride moieties of (XVII); T is xe2x80x94Oxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94SO2xe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94CyH2y group, a group of the formula xe2x80x94Oxe2x80x94Zxe2x80x94Oxe2x80x94, and mixtures thereof, where Z is a divalent moiety that is predominantly aromatic in nature, such as those in Formulae V; A is a divalent aromatic radical such as 1,2,4,5-phenylene, 2,3,6,7-naphthalene, combinations thereof, and the like.
Some examples of possible anhydrides include: phthalic dianhydride, 4,4xe2x80x2 oxy diphthalic anhydride, bisphenol A dianhydride, dimethyl siloxane dianhydride, benzophenone dianhydride, biphenyl dianhydride, diphenyl sulfone dianhydride, as well as aromatic bis(ether anhydride)s of Formula VIII, combinations thereof, and the like.
Other Additives
The thermoplastic resin composition of the present invention may optionally comprise various additives, such as antioxidants, for example, organophosphites, for example, tris(nonyl-phenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite or distearyl pentaerythritol diphosphite, alkylated monophenols, polyphenols and alkylated reaction products of polyphenols with dienes, such as, for example, tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane, 3,5-di-tert-butyl-4-hydroxyhydrocinnamate octadecyl, 2,4-di-tert-butylphenyl phosphite, butylated reaction products of para-cresol and dicyclopentadiene, alkylated hydroquinones, hydroxylated thiodiphenyl ethers, alkylidene-bisphenols, benzyl compounds, esters of beta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid with monohydric or polyhydric alcohols, esters of beta-(5-tert-butyl-4-hydroxy-3-methylphenyl)-propionic acid with monohydric or polyhydric alcohols; esters of thioalkyl or thioaryl compounds, such as, for example, distearylthiopropionate, dilaurylthiopropionate, ditridecylthiodipropionate, amides of beta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid; fillers and reinforcing agents, such as, for example, silicates, titanium dioxide, fibers, glass fibers (including continuous and chopped fibers), carbon black, graphite, calcium carbonate, talc, mica and other additives such as, for example, mold release agents, UV absorbers, stabilizers such as light stabilizers and others, lubricants, plasticizers, pigments, dyes, colorants, anti-static agents, blowing agents, flame retardants, impact modifiers, among others, and combinations thereof.
The preparation of the compositions of the present invention is normally achieved by merely blending the ingredients under conditions suitable for the formation of an intimate blend. Such conditions often include solution blending or melt mixing in single or twin screw type extruders, mixing bowl, roll, kneader, or similar mixing device that can apply a shear to the components. Twin screw extruders are often preferred due to their more intensive mixing capability over single screw extruders. It is often advantageous to apply a vacuum to the blend through at least one vent port in the extruder to remove volatile components in the composition.
Meanwhile, the blend is preferably sufficiently heated such that the components are in the molten phase, thereby enabling intimate mixing. Typically temperatures up to about 360xc2x0 C. can be employed, with about 220xc2x0 C. to about 350xc2x0 C. preferred, and about 260xc2x0 C. to about 340xc2x0 C. especially preferred.
The composition typically comprises, based upon the total weight of the composition, about 88 wt % to about 99 wt % of a thermoplastic polymer resin and about 1 wt % to about 12 wt % of an additive selected from the group consisting of phosphonium sulfonate, anhydride, and mixtures thereof, with about 93 wt % to about 99 wt % of the thermoplastic polymer(s) resin and about 1 wt % to about 7 wt % of the additive(s) preferred.